This invention relates generally to processes for decontaminating contaminated materials, such as chemical weapon components, and, more specifically, to processes for 5 decontaminating contaminated materials without using incineration methods.
The decontaminating of contaminated material can be very difficult. This is especially the case with respect to the decommissioning of chemical weapons carrying chemical warfare agents. The principal problem in this regard is how to safely remove, neutralize and dispose of the extremely toxic chemical warfare agents used in such chemical weapons. Modern technology has become increasingly successful in the neutralization of these chemical warfare agentsxe2x80x94once the agents have been removed from the chemical weapon housing. However, after the bulk of the chemical warfare agents have been removed from the chemical weapons housings, the housings and their various components typically remain contaminated with residual amounts of the chemical warfare agents. The decontamination of these chemical weapon components remains a difficult problem.
Most prior art methods for decontaminating chemical weapon components have employed a two-step process. In a first step, the components are subjected to liquid chemicals or to high temperatures to remove and decompose essentially all of the chemical warfare agents adhering to the chemical weapon components. In a second step, residual vapors from the first step are incinerated to eliminate any and all residual chemical warfare agents in those vapors.
The incineration step has now been questioned, however, as possibly allowing potentially toxic combustion products to be released to the atmosphere. Accordingly, the incineration step has been banned in many industrial countries, including in the United States.
A similar but separate problem is how to dispose of organic materials, such as wood, plastic, rubber, and cloth which is contaminated with hazardous agents. Traditionally, such organic materials must be disposed of in a special hazardous materials dump site. Since such organic materials tend to be bulky, the relative cost of disposing of such materials is very high.
Thus, there is a need for a new method of decontaminating chemical weapon components which completely eliminates all traces of chemical warfare agents in an efficient and inexpensive manner, and without the use of an incineration step.
There is a further need for a new method of disposing of organic materials which have been contaminated with hazardous materials, a new method which is also efficient and inexpensive in operation and which does not require the use of an incineration step.
The invention satisfies this need. The invention is a process for the low temperature, non-incineration decontamination of contaminated materials containing hazardous agents, the process comprising (a) mixing the contaminated metal components with organic solid materials to form a feed mixture containing metallic material and non-metallic material, (b) contacting the feed mixture with steam at substantially ambient pressure in a substantially dry first heated vessel for a period of at least about 15 minutes, the steam being at a temperature of at least about 560xc2x0 C., whereby essentially all of the hazardous agents are removed from the contaminated metal components, and whereby all of the non-metallic material within the feed mixture is volatilized, (c) removing a first gaseous discharge stream containing hazardous agents from the first heated vessel, the first gaseous discharge stream comprising a condensible moiety and a non-condensible moiety, (d) heating the first gaseous discharge stream at substantially ambient pressure in a substantially dry second vessel to at least about 500xc2x0 C. and maintaining the first gaseous discharge stream in the second vessel above at least about 500xc2x0 C. for a period of at least about one second in an atmosphere containing steam, whereby at least about 99 wt. % of the hazardous agents within the first gaseous discharge stream are converted to non-hazardous agents, (e) removing a second gaseous discharge stream containing a reduced concentration of hazardous agents from the second vessel, the second gaseous discharge stream comprising a condensible moiety and a non-condensible moiety, (f) having a concentration of hazardous agents less than about 100 mg/l, (g) increasing the pH of the condensate to at least about 8.0 so as to reduce the concentration of hazardous agents within the condensate to less than about 1.0 mg/, and (h) catalytically treating the non-condensible moiety of the second gaseous discharge stream in the presence of oxygen so that the concentration of hazardous agents within the non-condensible moiety of the second gaseous discharge stream is reduced to less than about 1.0 mg/m3 at standard temperature and pressure.
The process is especially applicable where the contaminated materials are chemical weapon components and the hazardous agents are chemical warfare agents.
The process is also especially applicable where the organic solid materials within the feed mixture comprise contaminated organic materials.